• Analytical Science and Technology
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• v.19 no.4
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• pp.285-289
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• 2006

In this study, the effect of an acidic treatment on granular activated carbon (GAC) and activated carbon fibers (ACF) was investigated for a $Pb^{2+}$ and $Ni^{2+}$ ion adsorption. 1.0 M nitric acid solution was used as the acid solution for the surface treatment. Surface properties of the GAC and ACF were characterized by the pH, elemental analysis and pHpzc (pH of the point of zero charge). Their specific surface area and the pore structure were also evaluated by the nitrogen adsorption data at 77K. As a result, the acidic treatment led to an increase of the oxygen-containing functional groups. Furthermore, the adsorption capacity of the acid-treated GAC and ACF was improved in the order of acidic-ACF > untreated-ACF > acidic-GAC > untreated-GAC, though the decrease in specific surface area induced by a pore blocking of the functional groups was observed.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.6
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• pp.157-162
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• 2023

A highly sensitive refractive index bio-sensor based on grating-assisted strip directional coupler (GASDC) is proposed. The sensor is designed using two asymmetric strip waveguides with a top-loaded grating structure in one of the waveguides. Maximum light couples from one waveguide to the other at the resonance wavelength satisfying phase-matching condition (PMC), and it shows that the change in phase-matching condition with the change in refractive index of the analyte medium in the cover region can be used as a measure of the sensitivity. The proposed sensor will be an on-chip device with a high refractive index sensitivity, and the sensor configuration offers a low propagation loss, thereby enhancing the sensitivity. Furthermore, variation of the sensitivity with the waveguide parameters of sensor is evaluated to optimize the design.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.5
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• pp.145-150
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• 2023

Non-uniform optical taper waveguides have been widely used as devices for high-efficiency mode coupling, as they are integrated with single-mode optical fibers or photonic crystal waveguides. In this paper, we present a new platform for chemical sensing and bio-sensing using optical taper waveguides with these characteristics. The principle of operation is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multi-mode interference coupler (MMIC). First, the curvature characteristics of taper sections of DC and MMIC is explained, and the design specifications of optimized taper waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the change in refractive index of sensing analyte is numerically analyzed. Numerical results show that as the length of couplers increases, the effective index per change in refractive index unit (RIU) of analyte increases, and that sensitivity can be tuned using taper DC and MMIC design techniques.

• Journal of the Society of Disaster Information
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• v.20 no.2
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• pp.419-429
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• 2024

Purpose: To enhance the non-combustibility of fire protection piping insulation and improve the heat resistance of smoke extraction duct insulation, I plan to verify the suitability of AES insulation materials for these applications through performance testing. Method: The non-combustibility, heat resistance, and thermal insulation performance of AES insulation materials will be verified through various tests. Result: According to the 'Standards for Flame Retardancy and Fire Spread Prevention of Building Finishing Materials,' the results of non-combustibility and gas toxicity tests confirmed the non-combustible properties. The standard fire resistance tests verified the fire resistance performance. Additionally, the thermal insulation performance was confirmed through building insulation tests. Conclusion: As the performance tests on AES inorganic insulation materials have proven their noncombustibility, fire resistance, and thermal insulation performance, these materials are considered a viable alternative for improving fire spread prevention in buildings.

• The Journal of the Acoustical Society of Korea
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• v.27 no.7
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• pp.372-378
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• 2008

Voice activity detectors (VAD) are important in wireless communication and speech signal processing, In the conventional VAD methods, an expression for the likelihood ratio test (LRT) based on statistical models is derived in discrete Fourier transform (DFT) domain, Then, speech or noise is decided by comparing the value of the expression with a threshold, This paper presents a new statistical VAD method based on a signal subspace approach, The probabilistic principal component analysis (PPCA) is employed to obtain a signal subspace model that incorporates probabilistic model of noisy signal to the signal subspace method, The proposed approach provides a novel decision rule based on LRT in the signal subspace domain, Experimental results show that the proposed signal subspace model based VAD method outperforms those based on the widely used Gaussian distribution in DFT domain.

• Korean Journal of Materials Research
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• v.34 no.6
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• pp.275-282
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• 2024

In this work, we investigated the photo-degradation performance of MnO₂-SiC fiber-TiO₂ (MnO₂-SiC-TiO₂) ternary nanocomposite according to visible light excitation utilizing methylene blue (MB) and methyl orange (MO) as standard dyes. The photocatalytic physicochemical characteristics of this ternary nanocomposite were described by X-ray diffraction (XRD), scanning electron microscopy (SEM), tunneling electron microscopy (TEM), ultraviolet-visible (UV-vis), diffuse reflectance spectroscopy (DRS), electrochemical impedance spectroscopy (EIS), photocurrent and cyclic voltammogram (CV) test. Photolysis studies of the synthesized MnO₂-SiC-TiO₂ composite were conducted using standard dyes of MB and MO under UV light irradiation. The experiments revealed that the MnO₂-SiC-TiO₂ exhibits the greatest photocatalytic dye degradation performance of around 20 % with MB, and of around 10 % with MO, respectively, within 120 min. Furthermore, MnO₂-SiC-TiO₂ showed good stability against photocatalytic degradation. The photocatalytic efficiency of the nanocomposite was indicated by the adequate photocatalytic reaction process. These research results show the practical application potential of SiC fibers and the performance of a photocatalyst composite that combines these fibers with metal oxides.

• Journal of Applied Biological Chemistry
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• v.66
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• pp.359-368
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• 2023

This study aims to explore the impact of Krill Oil (KO, Superba^TM Boost) on skin moisturization regulation. The research involved five groups: an intact control, a reference group (L-AA 100 mg/kg), and KO groups (400, 200, and 100 mg/kg), each comprising ten mice. Oral administration was conducted for 8 weeks (56 days), during which changes in body weight, hyaluronan, collagen type 1 (COL1), transforming growth factor-β1 (TGF-β1), ceramide, and water contents were analyzed in dorsal back skin tissue. Real-time PCR was employed to assess gene expression related to hyaluronic acid synthesis (HAS1, HAS2, HAS3), COL1 synthesis (COL1A1 and COL1A2), and TGF-β1. Results demonstrated that KO administration significantly increased hyaluronan content, hyaluronic acid synthesis (HAS1, HAS2, HAS3), COL1 content, COL1 synthesis (COL1A1 and COL1A2), TGF-β1 content, TGF-β1 mRNA expression, ceramide content, and water content in a concentration-dependent manner compared to the intact control. Importantly, no discernible disparities were noted between the KO and L-AA groups, even though they received equivalent oral dosages. This study accentuates the potential utility of exogenous KO in the regulation of skin moisture, thus positioning it as a promising avenue for the development of nutricosmetics. Future research endeavors should delve into the role of KO in safeguarding against both intrinsic and extrinsic aging-related skin manifestations, as well as its potential to ameliorate skin wrinkles, in conjunction with its moisturizing attributes.

• Journal of the Korean Society of Radiology
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• v.84 no.6
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• pp.1373-1377
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• 2023

Immunoglobulin G4 (IgG4)-related lung disease can have various clinical courses. To our knowledge, reports of IgG4-related lung disease with waxing and waning pulmonary infiltrates only are very rare. A few lung nodules and ground glass opacities were incidentally found in a pre-operative evaluation in a 36-year-old female. The lung lesions showed waxing and waning in the follow-up chest CT. She underwent a surgical biopsy, and IgG4-related lung disease was confirmed.

• Annals of Hepato-Biliary-Pancreatic Surgery
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• v.26 no.1
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• pp.1-16
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• 2022

Pancreatic cancer is the eighth most common cancer and the fifth most common cause of cancer-related deaths in Korea. Despite the increasing incidence and high mortality rate of pancreatic cancer, there are no appropriate surgical practice guidelines for the current domestic medical situation. To enable standardization of management and facilitate improvements in surgical outcome, a total of 10 pancreatic surgical experts who are members of Korean Association of Hepato-Biliary-Pancreatic Surgery have developed new recommendations that integrate the most up-to-date, evidence-based research findings and expert opinions. This is an English version of the Korean Surgical Practice Guideline for Pancreatic Cancer 2022. This guideline includes 13 surgical questions and 15 statements. Due to the lack of high-level evidence, strong recommendation is almost impossible. However, we believe that this guideline will help surgeons understand the current status of evidence and suggest what to investigate further to establish more solid recommendations in the future.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.4 s.56
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• pp.126-136
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• 2009

The sprayed FRP strengthening technique is combining the Glass fiber and Polyester resin in open air and spraying randomly at concrete's surface with high-speed compressed air. Then it strengthens the structures with a new technique evaluated the structural performance. We applied it to concrete beam and tested for flexural strength, depended on Korea Standard(KS F 2408). Then based on the result of flexural strength, the properties were proposed that applying to structures. Based on the experiment, we have evaluated structural performance by the experiment. 1/5 scale prestressed concrete I-beam were made by Korean Highway's typical drawing in 1993. With these test results, 49.8% increased in flexural strength, improvement of the behavior of serviceability state, and strengthening was surely effective for controlling deflection and crack of structure. Consequently, it can be summarized that Sprayed FRP technique has prospect to improve the performance of structure.